| . |
The period (.) matches any single character. |
| ? |
The preceding item is optional and will be matched at most once. |
| * |
The preceding item will be matched zero or more times. |
| + |
The preceding item will be matched one or more times. |
| {n} |
The preceding item is matched exactly n times. |
| {n,} |
The preceding item is matched n or more times. |
| {,m} |
The preceding item is matched at most m times. |
| {n,m} |
The preceding item is matched at least n times, but not more than m times. |
| [:alnum:] |
Alphanumeric characters: '[:alpha:]' and '[:digit:]'; in the 'C' locale and ASCII character encoding, this is the same as '[0-9A-Za-z]'. |
| [:alpha:] |
Alphabetic characters: '[:lower:]' and '[:upper:]'; in the 'C' locale and ASCII character encoding, this is the same as '[A-Za-z]'. |
| [:blank:] |
Blank characters: space and tab. |
| [:cntrl:] |
Control characters. In ASCII, these characters have octal codes 000 through 037, and 177 (DEL). In other character sets, these are the equivalent characters, if any. |
| [:digit:] |
Digits: 0 1 2 3 4 5 6 7 8 9. |
| [:graph:] |
Graphical characters: '[:alnum:]' and '[:punct:]'. |
| [:lower:] |
Lower-case letters; in the 'C' locale and ASCII character encoding, this is a b c d e f g h i j k l m n o p q r s t u v w x y z. |
| [:print:] |
Printable characters: '[:alnum:]', '[:punct:]', and space. |
| [:punct:] |
Punctuation characters; in the 'C' locale and ASCII character encoding, this is! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ' { |
| [:space:] |
Space characters: in the 'C' locale, this is tab, newline, vertical tab, form feed,carriage return, and space. |
| [:upper:] |
Upper-case letters: in the 'C' locale and ASCII character encoding, this is A B C D E F G H I J K L M N O P Q R S T U V W X Y Z. |
| [:xdigit:] |
Hexadecimal digits: 0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f. |
| \b |
Match the empty string at the edge of a word. |
| \B |
Match the empty string provided it is not at the edge of a word. |
| \< |
Match the empty string at the beginning of word. |
| > |
Match the empty string at the end of word. |
| \w |
Match word constituent. Synonym for '[_[:alnum:]]'. |
| \W |
Match non-word constituent. Synonym for '[\^_[:alnum:]]'. |
| \s |
Match white space. Synonym for '[[:space:]]'. |
| \S |
Match non-whitespace. Synonym for '[^[:space:]]'. |